Cartridge ferrule type refillable fuse and element



0t 15, 1935. J. B. GLowAcKl CARTRIDGE FERRULE TYPE REFILLABLE FUSE AND ELEMENT Filed March 24, 1954 2 Sheets-Sheet l HE7-2 z J7 5' fsulafion f* l@ EME-M235 y /5 @M 'y hg Z;

@CL s, 1935. Jua GLOWACK| 2,017,492

CARTRIDGE FERRULE TYPE REFILLABLE FUSE AND ELEMENT Filed March 24,1934 2 Sheeos--SheeI 2 Eig; 9

l cL/cabe. g oo o 0 Patented Oct. 15, 1935 UNITED STATES PATENT OFFICE CARTRIDGE FERRULE TYPE REFILLABLE FUSE AND ELEMENT 11 Claims.

This invention relates to an improved type of cartridge ferrule type refillable fuse and fuse element unit wherein the fuse element is removably engaged on an insulation holder or core clamped between the inner ends of -insulation covered contact bushings which are secured within end caps removably engaged on the ends of the fuse casing, said contact bushings having gas chambers filled with a porous material such as superimposed layers of Wire screening.

It is an object of this invention to provide a cartridge type fuse wherein an insulation casing has metal caps removably engaged on the ends thereof with said caps having secured therein bushing units which contact end portions of a fuse element supported in position on. an insulation holder or core disposed within the fuse casing.

It is also an object of this invention to provide an improved type of cartridge fuse having an insulation holder or core removably engaged therein for supporting a replaceable fuse element in a deiieeted form longitudinally within the holder or core unit.

It is a further object of this invention to provide a cartridge ferrule type fuse with a replaceable fuse element supported in position on an inlsulation holder or core having portions thereof formed for the element to be deflected therearound andYV lie in an irregular path within the fuse casing.

It is furthermore an object of this invention to provide a cartridge ferrule type fuse wherein the removable end caps of the casing have chambered contact bushings secured therein filled with wire screening and molded within insulation coverings leaving the inner ends of the bushings uncovered to serve as contacts for engagement with the end portions of a fuse element disposed within the fuse.

It is an important object of this invention to provide a cartridge ferrule type reiillable fuse and fuse element unit having removable end caps to facilitate replacement of blown fuse elements or a fuse element cartridge clamped between the inner ends of insulated Contact bushings having vent apertures therein leading to gas chambers which lled with wire screening to serve as a means for breaking up and reducing the speed of discharge of hot air and gases from the ends of the fuse after the blowing of a fuse element.

Other and further important objects of this invention will be apparent from the disclosures inthe speciiication and the accompanying drawings.

The invention (in a preferred form) is illustrated in the drawings and hereinafter more fully described.

On the drawings: l

Figure l is an elevational view of an improved cartridge ferrule type refillable fuse embodying the principles of this invention.

Figure 2 is a longitudinal sectional View of the fuse showing interior parts in elevation and in section.

Figure 3 is an enlarged longitudinal sectional view of the fuse taken on line III--III of Figure 2.

Figure 4 is a transverse on line IV-IV of Figure 3.

Figure 5 is a transverse detail section taken on line V-V of Figure 3.

Figure 6 is a transverse detail section taken on line VI-VI of Figure 3.

Figure 7 is an elevational view of the fuse element holder or core unit removed from the fuse casing.

Figure 8 is a side view of the fuse element removed from the fuse partially bent for mounting on the fuse element holder and showing the end portions in dotted lines bent into final positions of engagement after the element has been en gaged through the holder.

Figure 9 illustrates a longitudinal section, similar to Figure 3, taken through a modied form of ruse.

Figure 10 is a plan View of a modified form of fuse element indicating in dotted lines the positions for deflecting or bending the element to facilitate mounting of the same in a modified form of element holder or core.

Figure 1l is an enlarged fragmentary elevational and sectional view of another modified form of fuse wherein the fuse casing is formed of molded insulating material and has threaded metal thimbles molded around the reduced end portions thereof with means for holding the thimbles locked against rotation with respect to the casing.

Figure 12 is an enlarged inner end view of the modified form of contact bushing for the form of modified fuse illustrated in Figure 9.

Figure 13 is an elevational view of a modiiied form of fuse element supporting core or holder of the type used in the modiiied form of fuse i1- lustrated in Figure 9.

Figure 14 is a partly broken away elevational View of a modified form of fuse element cartridge type unit for use in the fuse in place of the fuse detail section taken til element and holders of the types illustrated in Figures 3 and 9.

As shown on the drawings:

The reference numeral I indicates a molded type of insulation fuse casing having the exterior of the main body portion thereof of multiple-sided or octagonal shape with the flat surfaces 2 thereof serving as a means to prevent rolling `of the fuse when placed on a fiat surface and also affording a suitable gripping arrangement for holding the fuse during the assembly thereof. 'Ihe fuse casing I is provided with reduced exteriorly threaded end portions or sleeves I.

Removably engaged in the insulation casing I substantially midway between the ends thereof il a removable fuse unit comprising a holder or core and a fuse element. The element holder consists of a pair of insulation side or longitudinal members 4 having straight inner surfaces and curved outer surfaces which are curved complementally to the curvature of the inner surface of the fuse casing I. Integrally connecting the two side members 4 of the core are a pair of spaced connecting blocks or bridge pieces which have the outer ends thereof flush with the outer ends of the longitudinal or side members 4 of the core. As clearly illustrated in Figure 3 the connecting blocks 5 are tapered inwardly from both ends toward the center to provide inclined meeting surfaces 6 and 1. As clearly illustrated in Figure 3 the inner ends of the fuse element supporting blocks 5 are spaced apart.

Removably supported longitudinally within the removable insulation element holder or core unit is the replaceable fuse element which embraces a main fuse strip l having pairs of notches 9 in the longitudinal margins thereof and also hav ing irregular slots I0 positioned between the pairs of notches I to form fusing strips II. The end portions of the fuse element B are bent in oppostte directions along the transverse lines at points I2 and I2 to form hook members comm prising an outer flap or end section I4 and a conw tact plate section I5. The main body portieri of the fuse strip is deflected along the transverse lines at points I8. The fuse element is normally provided in the shape substantially that 4illustrated in Figure 8 to facilitate engagement of the fuse element longitudinally within the element supporting core unit as illustrated in Fig- '.lre 3. The fuse element is inserted diagonally through the space between the inner ends of the 5 core blocks 5 allowing the hook-shaped ends of the fuse element to be engaged around the outer ends of the blocks 5 in opposite directions to form an element of substantially S-shape with the contact portions I5 deflected into the dotted line positions of Figure 8 to lie fiat against the outer ends of the supporting blocks 5 while the end naps I4 of the fuse element lie flatly against the inclined surfaces 6 of the connecting blocks. With the fuse element in position as described and 'as illustrated in Figure 3 the narrow fusing y caps I1 is provided with a; circular groove 2I.

Rigidly secured within the hood portion I8 of the cap I1 is a contact bushing comprising a cylindrical contact block 22 having integrally formed on one end thereof a hollow sleeve 23 which affords a hot air and gas escape chamber which is filled with a porous material such as a coil of wire screening 24. If desired the porous filling may consist of a stack of wire screen plates or discs such as illustrated in Figure 8 which will be hereinafter again referred to. The sleeve portion 23 of the bushing is provided with a plurality of vent openings 25 which register with escape or vent openings 26 which are provided in an insulation covering or sleeve 21. The insulation sleeve 21 is held in position against rotation on the bushing by the straight knurled outer surface 28 which extends from the inner end of the bushing to within a short distance of the outer end leaving a plane exterior ring surface 29 as clearly illustrated in Figure 2. The straight outer surface 29 of the bushing permits the bushing to be inserted into the hood portion I8 of the cap through the inner cap groove 2i and allows a portion of the knurled surface 28 to tightly out into the inner surface of the hood I8 to hold the bushing secured in place. When a closure cap I1 is engaged in position on the end of the fuse casing the inner end of the contact bushing 22 is pressed tightly against the contact plate section I5 of one end of the fuse element so that the retaining cap is connected with the fuse element through the bushing member. As clearly illustrated in Figure 3 the outer peripheral surface of the insulation sleeve or covering 21 of the bushing is spaced from the inner surface of the fuse casing I. With the two ends caps removably engaged on the ends of the fuse casing the fuse element is tightly clamped in position between the inner ends of the contact bushings.

With the fuse element secured in lposition as illustrated in Figure 3 it will be noted that the element is substantially surrounded by insulation with the exception of the hooked end portions of the element which arein contact with the contact bushings. When the fuse isconnected in a circuit and an excess current or a short circuit occurs the fuse element 8 will blow, melting the narrow fusing strips II and causing the middle portion of the fuse element to drop out or into the insulation casing to break the circuit. The hot metal resulting from the blowing of the fuse will not adhere or fuse with the insulation material forming the casing or the fuse element supporting core thereby eliminating the possibility of clogging up of the interiorvof the fuse casing.

animos screen filling of the contact members act to not only cool off the hot air and gases but also tend to greatly diminish the rate of speed thereof so that by the time the air and gases reach the outlet openings rIS/'in the ends of the closure caps the air andfg/as slowly escape. Any flames which might result from the blowing of the fuse element within the casing are broken up and ex' tinguished long before they reach the exit openings I9 in the ends of the fuse caps.

Figures 9, 10, 12, and 13cover a modified form of cartridge ferrule type reflllable.fuse comprising an insulation casing and metal end caps similar to the type illustrated and described in connection with Figures 1 to 8 of the drawings.

In this form of the fuse a modified removable fuse unit is engaged in the insulation casing I and comprises a fuse element and a holder or core for supporting the same in place. The ele- 1 ment supporting `holder or core comprises a pair of parallel insulation side members or longitudinal members 30 having straight inner surfaces and curved outer surfaces shaped complementally to the curvature of the inner surface of the casing I. The two side insulation members 30 are connected at the ends by end insulation bolcks 3I and intermediate the ends by an intermediate or middle connecting block or bridge piece 32.

The fuse element for use in the holder or core,

' comprises a fuse strip 33 having pairs of oppositely positionednotches 34 provided inthe longitudinal margins thereof. Also provided in the fuse strip 33 are irregular slots or openings 35 which are positioned between the pairs of notches 34 (Figure 10) to form narrow fusing strips 36. Also provided in the longitudinal margins of the main fuse strip 33 between the notches 34 and the ends of the strip are segment-shaped notches 31 leaving tapered fusing or blowing strips 33 which are substantially twice the width, at their narrowest points, of the blowing or fusing strips 36. The main fuse strip is adapted to be deected along the dotted lines 39, transversely of the fuse strip and along transverse lines crossing "the inner ends of the small fusing strips 36. The

end portions of the main fuse strip are bent upwardly and then inwardly toward one another to form hook-shaped end portions 40 adapted to be engaged around the outer ends of the end blocks or bridge members 3l forming part of the core as clearly illustrated in Figure 9. The middle portion of the main fuse strip 33 is deilected upwardly to form an arched middle portion which engages over the top or one side of the middle bridge block 32 so that the portions of the fuse element between the notches 31 and 34 lie in an inclined or diagonal position between the middle block 32 and the end blocks 3i'. The hooked end portions E@ of the fuse strip have contact plate portions 4I which lie dat against the outervends of the end bridge blocks 3l. Each of the end blocks 3l tapers inwardly from both ends toward the center to provide converging inclined surfaces 42 and 43. as clearly illustrated in Figure 9 the extrenieiend portions or iiaps of the fuse strip 33 lie fiat against the inclined surfaces 42 at one side of the two end blocks 3i.

For the purpose of contacting the contact plate 4portions 4I at both ends of the fuse strip when in position within the fuse casing each of the end caps IT is provided with a contact unit which is secured therein and which comprises a contact bushing Q4 having an axial passage 45 pro` vided in the inner end thereof the outer end of which communicates with a diametrical groove eige 52,59

or passage 46. The outer end porton ci the husiiq ing 44 is provided with a pocket or chamber which the outer end of the axial passage comm municates. Disposed within the bushing cham ber is a lling of porous material in the form oi a stack of adjacently positioned wire screen discs 41 or by a coil of Wire screening such as is illus trated in Figure 3 of the drawings. As shown in Figure .9 the outer ends of the wire screen iilirig are disposed adjacent the inner ends of the open-u ings I9 provided in the outer ends oi the hood or boss Vportions I8 of the end caps. Molded or secured around the straight knurled exterior surface of the major portion of the bushing it is a covering or sleeve of insulation materiai similar to the construction illustrated in Figure it The knurling on the outer surface of the bush ing 44 extends beyond the outer end of the in -sulation sleeve 48 to within a short distance ci the outer end of the bushing leaving a smooth n or plane portion 29 around Vthe exterior oi' in s bushing as illustrated in Figure 2. This `arrangement facilitates mounting of the contact lunit within the hood portion I8 of an end cap so that the exposed knurled portion of the bushing las yond the outer end of the insulation sleeve is permitted to cut into the inner surface oi the cap hood I8 to rigidly hold the contact bushing in position and against rotation with respect to the end caps. y As clearly illustrated in Figure 12 the diametri cal groove 46 provided in the inner end oi the bushing 44 extends into the insulation sleeve 48.

When the fuse of the type illustrated in Figure 9 is connected in a circuit and an excessive 35- current or a short circuit occurs in the circuit the melting strips 36 of the fuse element will blow thereby severing the connection between the middle part of the fuse element from the inclined parts disposed on opposite sides of the middle 40y bridge portion 32 or the fuse element supporting core. The circuit is thus broken and in view of the fact that the element is supported on an insulation core and within an insulation casing the hot metal resulting from the blowing of the fuse 45' elementdoes not adhere to the parts so that the interior of the fuse is not clogged up. The hot air and gases resulting from the blowing of the fuse are permitted to escape fromthe ends of the fuse through the diametrical' slots 4B and 50 the axial slots 45 into the end chambers of the contact bushings into contactl with the wire screen lling which acts to greatly reduce the speed of the hot gases and air to such an extent that the time they reach the outlet openings I! in rthaends of the caps the hot air and gases slowly escape.v Attention is also called to the fact that any iiames which may result from the blowing of a fuse element Within the casing are extinguished or broken up by the Wire screen G0 filling 4.1 so that no flames are discharged through the ends of the fuse. v

Figure 11 illustrates another modiiied form of cartridge ferrule type reflllable fuse similar to that illustrated in Figures 1 and 2with the ex- 655" ception that in this form of the fuse the molded insulation casing I hasmetal threaded thimbles 49 molded around the reduced'end sections 3 oi' the fuse casing. Each of the threaded metal thimbles 49 is provided with an inner flange 50 7 having deilected portions 5I which project into4 the material forming the molded fuse casing I to hold the thimbles locked against 'rotationwith respect to the fuse casing.

Figure 14 illustrates a modified form of fuse '"5 element unit which may be used in the fuse casing of the fuses illustrated in Figures l to 13 inclusive in place of the fuse element and the insulation holders or cores hereinbefore described. The modified form of fuse element unit is of the cartridge type and comprises an apertured fiber or insulation sleeve 52 having metal end caps 53 secured on the ends thereof in which the outer ends o! a fusing strip or element 54 are secured. The fusing element 54 may be a strip o! fusing material or a fuse Wire as desired. The interior of the perforated sleeve 52 is provided with a filling 55 of shredded insulating material.

The fuse element unit illustrated in Figure 14 may be engaged in a fuse casing I and is adapted to be held in position between the inner ends of the contact units engaged within the fuse caps I1. When the fuse element 54 is blown the entire fuse unit may be removed from the casing I and a new unit substituted in place thereof.

It will of course be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is therefore not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. A cartridge ferrule type refillable fuse comprising an insulation casing, an insulation core removably engaged in the casing, a fuse element supported on the insulation core, metallic end caps removably engaged on the ends of the insulation casing, metallic contact means in the end caps projecting inwardly into contact with the fuse element, and insulation coverings engaged around the contact means to separate the same from the casing.

2. A cartridge ferrule type refillable fuse comprising an insulation' casing, an insulation core unit therein, a fuse element mounted to follow an irregular path through the insulation core, metallic end caps removably engaged on the ends of the casing, apertured contact means secured in the caps and projecting into the casing into contact with the fuse element, iillings of porous material engaged in the contact means and in contact with the end caps, and apertured sleeves sexcured around the contact means with the apertures in said sleeves registering with. the apertures in the contact means.

3. A cartridge ferrule type reiillable fuse comprising an insulation casing, a fuse element supporting core removably engaged in the casing, a fuse element removably engaged through the core and projecting across the ends thereof, apertured caps removably engaged on the ends of the casing, apertured and chambered contact means secured in the caps and projecting into the casing into contact with the end portions of the fuse element, apertured insulation sleeves molded around the contact means with the apertures in said sleeves registering with the apertures in the contact means, and wire screen fillings disposed in the chambers of the contact means and in contact with the apertured end caps.

4. A cartridge ferrule type refillable fuse including in combination a fuse element supporting unit comprising a pair of spaced parallel insulation members, insulation end pieces connecting the ends of the insulation members, and an intermediate insulation bridge piece connecting the insulation members and spaced `trom the insulation end pieces, and a fuse element between the insulation members and laced around the insulation end pieces and the insulation bridge piece.

5. A fuse of the character described including in combination a fuse element support comprising a pair of spaced parallel insulation members, insulation end blocks connecting the ends of the insulation members, and an insulation bridge piece connecting the intermediate portion of the insulation members and spaced from the insula tion end pieces.

6. A fuse of the class described including in l combination a casing, a cap removably engaged on one end thereof, an apertured and chambered metal bushing rigidly secured in the cap and projecting into the casing, a filling of porous material engaged in the chambered portion of the bushing, and an insulation covering engaged around the portion of the bushing which projects into the fuse casing.

'7. A fuse of the class described including in combination a casing, an apertured cap removably engaged on the end thereof, an apertured and chambered metal bushing rigidly secured in the cap and projecting into the casing, a filling o! wire screening engaged in the ch ambered portion of the bushing and in contact with the cap, and a covering of insulation material engaged around the portion of the bushing projecting into the casing.

8. A cartridge ferrule type replaceable fuse comprising an insulation casing, metal end caps removably engaged on the ends of the casing, contact members secured in the caps and projecting into the casing, filling means within the contact members and having circuitous passages therein, insulation coverings on the contact means to separate the same from the casing, and a replaceable fuse element unit removably en gaged in the casing and clamped between the inner ends of the contact members.

9. A cartridge type fuse including in combination a casing end closure unit comprising an apertured metal cap, an exteriorly knurled contact bushing rigidly secured in the cap, an insulation covering engaged around the knurled portion of the bushing, said bushing having a chamber therein, a diametrical groove in the inner end oi the bushing and an axial passage connecting the groove with the bushing chamber, and a circuitously passaged iilling deposited in the bushing chamber and in contact with the apertured portion of the capl 10. A fuse including in combination a casing having an end closure comprising an apertured cap, an apertured and chambered contact means in the cap, a Iilling of porous material in the contact means chamber, and an apertured covering of insulation engaged around the apertured contact means.'

ll. A cartridge ferrule type fuse comprising a casing, end closures thereon, an insulation holder in the casing including spaced insulation mem bers and insulation bridge pieces connecting said members, each of said bridge pieces formed with inwardly inclined surfaces, and a fuse element supported on said holder and having hooked end portions engaged around the bridge pieces with the ends of said hooked end portions deflected inwardly into contact with the inclined surfaces of the bridge pieces ree from possible contact with the inner surface of the fuse casing.

JOHN B. GLOWACKI. 

